Effect of Compton Scattering on the Borrmann Effect of X-Rays in Silicon Crystals

Abstract

The absolute integrated intensities diffracted in anomalous transmission through thick, nearly perfect crystals of silicon were measured for AgKα and MoKα wavelengths and for the {220} reflection, at room and liquid nitrogen temperatures. There is good agreement between experimental values and those calculated by using the formulas of the dynamical theory of diffraction, provided the contribution of Compton scattering μC* is included in the effective absorption coefficient μ*. μC* is a considerable fraction of μ* (from 23 to 55 per cent) for the two wavelengths and temperatures used in the present work. The experimental values of μC* agree well with those calculated by using the theory of the Compton contribution to the dynamical absorption coefficient of X-rays. A simple formula which is a good approximation of the rigorous expression of μC* is also given. The Debye temperature Θ of Si was derived from the experimental dependence of the intensities on crystal thickness for the {220} reflection at room and liquid nitrogen temperatures by using CuKα radiation. It was found that Θ = 521+5 and 543 + 5 °K at 295 and 77 °K, respectively, in agreement with the results of other authors.